Magnification
M magnification, I image size, A actual size.
M = I / A IB Middle Years Programme 2026
🧬 IB MYP Biology Formula Sheet
Essential formulas for cells, genetics, ecology, and biological calculations across MYP Years 1-5.
Cells Genetics Ecology
Understand Biological Relationships
This formula sheet covers fundamental biology relationships from MYP Years 1-5, helping you solve problems involving cells, genetics, and ecosystems.
🔬
Cell calculations
🧬
Genetics formulas
🌿
Ecology relationships
📊
Data analysis
Cell Biology & Microscopy
Calculations involving cell size, magnification, and microscopy.
Actual Size
Calculate actual size from image size and magnification.
A = I / M Image Size
Calculate image size from actual size and magnification.
I = A × M Surface Area to Volume Ratio
Important for understanding cell size limitations.
Smaller cells have higher SA:V ratios, allowing more efficient exchange.
SA:V = Surface Area / Volume Topic Focus
Microscopy Calculations
- Always use the same units for image size and actual size (usually micrometers, μm).
- Magnification has no units—it's a ratio.
- Convert units if needed: 1 mm = 1000 μm, 1 cm = 10,000 μm.
Cell Size & Exchange
- Smaller cells have larger surface area relative to volume (higher SA:V ratio).
- High SA:V allows efficient exchange of materials (nutrients, waste, gases).
- This is why cells are small—larger cells would struggle with material exchange.
Genetics & Inheritance
Basic genetic calculations and inheritance patterns.
Genotype Ratio
Ratio of different genotypes in offspring.
Use Punnett squares to predict genotype and phenotype ratios.
Phenotype Ratio
Ratio of different phenotypes in offspring.
Phenotype = observable characteristics (e.g., tall/short, red/white flowers).
Topic Focus
Genetic Crosses
- Use Punnett squares to predict offspring genotypes and phenotypes.
- Genotype = genetic makeup (e.g., TT, Tt, tt). Phenotype = physical appearance.
- Dominant traits mask recessive traits in heterozygous individuals.
Ecology & Populations
Population growth, density, and ecosystem calculations.
Population Density
Number of individuals per unit area.
Population Density = (Number of Individuals) / (Area) Population Growth Rate
Change in population over time.
Growth Rate = ((Final Population - Initial Population) / Initial Population) × 100% Percentage Cover
Percentage of area covered by a species.
% Cover = (Area Covered by Species / Total Area) × 100% Topic Focus
Population Studies
- Population density helps compare populations in different areas.
- Growth rate can be positive (increasing) or negative (decreasing).
- Percentage cover is useful for studying plant communities in quadrats.
How to Use This Formula Sheet
Boost your Cambridge exam confidence with these proven study strategies from our tutoring experts.
🔍
Use Correct Units
Always check units match in calculations. Convert between mm, cm, m, and μm as needed.
📊
Draw Diagrams
Sketch Punnett squares, cell structures, or ecosystems to visualize relationships before calculating.
Excel in MYP Biology
Master biology concepts with expert MYP tutors who help you understand living systems and solve biological problems confidently.
Formulas align with IB MYP Biology curriculum for Years 1-5 (ages 11-16).
Always show your working, include units, and check that answers make biological sense.